Dynamic response of single coal-rock impacting tail beam of top coal caving hydraulic support

The impact load caused by coal-rock caving in the process of comprehensive mechanized top coal caving mining will lead to the change of movement state of hydraulic support for top coal caving,if the impact load is serious, it will cause the impact damage of fully mechanized caving equipment. In order to study the dynamic responses and stress condition of the tail beam of the top coal caving hydraulic support after the impact of coal-rock,this paper used mechanical system dynamics analysis software Adams to establish the rigid-flexible coupling model of caving mecha-nism and calculate the stiffness of tail beam jack by solid-liquid spring coupling theory,then replaced the jack with a spring-damping system equivalently. This paper used the method of “coal-rock impacts the tail beam directly” to add load onto tail beam,and the contact parameter was determined by Hertz contact theory. Based on the rigid-flexible cou-pling model,the dynamic process of coal-rock impacting the tail beam at different positions and different coal caving angles was simulated. Finally,the reliability of the method was verified by comparing with the simulation results ob-tained by the way of rigid body impact. The results showed that the collision contact force and the dynamic response of tail beam were different when coal-rock impacts the different positions of bearing zone,if the impact location is near the tail beam-spring connection,the contact force is smaller,while the maximum velocity,acceleration and amplitude of the tail beam are larger. Among all the dynamic responses,the variation of maximum amplitude was the most obvious, it increased steadily as the position of impact point was far away from the area near the hinge of the tail beam and the shield beam. When the caving angle increased gradually,the dynamic responses of the tail beam and contact force de-creased,and the vibration characteristics of the tail beam became weak. If the caving angle is small,the impact of coal-rock will produce a huge numerical impact contact force. The amplitude response of the tail beam can be selected as the feedback quantity for dynamic monitoring of the tail beam. At the same time,to avoid the occurrence of impact damage of the tail beam and its connections,the strength check and structure optimization of the caving mechanism should be carried out during the design and manufacture of the caving mechanism in the case of a large collision con-tact force.